This application claims the benefit of Taiwan application Serial No. 105118389, filed Jun. 13, 2016, the subject matter of which is incorporated herein by reference.
Technical Field
The disclosure relates to a light emitting diode packaging structure, and more particularly to a light emitting diode packaging structure having a lens.
Description of the Related Art
Due to advantages of long lifetime, small volume, great resistance to vibration, low heat emission, and low power consumption, light emitting diodes (LEDs) have been extensively applied in various home appliances and instruments as indicators or light sources. With recent development towards multicolor and high illumination, the applications of the LEDs are extended to various display devices, lighting devices, etc.
A displaying effect of a product would be affected by a luminescence property of a device.
For example, a liquid crystal display device may use a back light module. A direct type back light module may use a light emitting diode as a light source together with a lens.
A scheme of a direct type light emitting module uses a reflective lens, which can lead the majority of a light from a light emitting diode toward a bottom surface of a module with having a larger light-mixing pathway. This scheme can achieve a thinner design. However, a manufacturing process for the device often requires a high accuracy and relates to a pack plate design for a module, with high technical difficulty. In addition, a tolerance for an optical shift is low. Therefore, there are the problems of risk of disposing an element and cost needed to be overcome.
Another scheme of the direct type light emitting uses a refractive lens, which can directly lead a light from a light emitting diode as a light source to a plane to be imaged by the lens. The scheme using the reflective lens has a larger manufacturing tolerance. However, it is very difficult to achieve a thin product when using the refractive lens with limitation of its physical threshold. Moreover, there is an undesirable optical phenomenon resulted from a shift of disposing an element during assembling a whole module, which relates to an accuracy problem of the disposing step.